Magnetic control apparatus for musical instruments



y 1937- v. H. SEVERY 2,078,979

MAGNETIC CONTROL APPARATUS FOR MUSICAL INSTRUMENTS 8 Sheets-Sheet 1 Filed July 10, 1953 V/cfor' /7! 56 very INVENT R. BY $M ATTORNEYS.

May 4, 1937. v. H. SEVERY MAGNETIC CONTROL APPARATUS FOR MUSICAL INSTRUMENTS Fil ed July 10, 1955 8 Sheets-Sheet 2 INVENTOR. BY fig ATTORNEYS.

May 4, 1937.

v. H. SEVERY MAGNETIC CONTROL APPARATUS FOR MUSICAL INSTRUMENTS Filed July 10, 1935 8 Sheets-Sheet 3' VII/4 ZIII/III/IIIIII/A vw N. e R m m #m W f w May 4, 1937. V; SEVERY 2,078,979

MAGNETIC CONTROL APPARATUS FOR MUSICAL INSTRUMENTS I Filed July 10, 1955 8 Sheets-Sheet 4 m I eE m .C V

k\\\ 'I/IIIIIIIIIIIIIIIIIIIIII y 937. v. H. sEvERy 2,078,979

MAGNETIC CONTROL APPARATUS FOR MUSICAL INSTRUMENTS Filed July 10, 1955 8 Sheets-Sheet 5 Victor /7. Severy v INVENTOR.

ATTORNEYS.

V. H. SEVERY May 4, 1937.

MAGNETIC CONTROL APPARATUS FOR MUSICAL INSTRUMENTS Filed July 10. 1935 8 Sheets-Shegt 6 V/cfor/i Seve/y A Home} y 1937- v. H.ISEVERY 2,078,979

MAGNETIC CONTROL APPARATUS FOR MUSICAL INSTBUMENTS Filed July 10, 1955 8 Sheets-Sheet 7 Inventor 33' Vicor bf Eel/erg v By 7 7 Attorney 3 MAGNETIC CONTROL APPARATUS FOR MUSICAL INSTRUMENTS Filed July 10, 1.935 1 s Sheets- Sheet a Inventor l/l'cfor Severy Attorney s Patented May 4, 1937 UNITED STATES PA EN OFFICE MAGNETIC CONTROL APPAEATUS Foil MUSICAL INSTRUMENTS Victor B. Severy, Loo-Angela, CaliL, asaignor Creative Industries, Inc., a corporation of Nevada Application July 10, 1933, Serial No. 679,632

11 cum. 84-259) This invention relates to magnetic apparatus for actuating vibrators, and the invention is particularly applicable when employed for vibrating the vibrators of musical instruments; and while the invention can be applied to different musical instruments, in the present specification, it is described as applied to a piano.

One of the objects of the invention is topro- 20 it is designed, adjacent to the piano strings This enables an ordinary piano to be transformed so that it can perform the functions and attain the charming musical efiects of a costly organ. I

spaced elements or poles." The rotor is rotated at a predetermined speed, so that the poles will 30, Pass the string at a frequency corresponding substantially to the period of vibration of the string. Through the actionof magnetic or electromagnetic forces, impulses are given to the string periodically, at the same frequency as the 5 natural period of vibration of the string. In this 'way the string produces its note. One of the objects of the invention is to provide apparatus.

of this kind, of simple and compact construction, which can readily be mounted adjacent to 40 the piano strings for controlling their vibration.

by depressing the piano keys; also to provide means whereby harmonic vibrations may be developed at will by the musician, by the simultaneous vibration of strings higher up in the'scale, 45 and without striking the key corresponding to the string that is higher in the scale. A further object of the invention is to provide a construction for the rotors, which maybe employed when desired, to produce harmonic 50 vibrations in the strings.

A further object of the invention is to provide simple means for controlling the volume of the tones produced by the vibrators or strings.

A iurther object of the invention is to provide 55 simple means for developing impulses in an el c- In employing the invention, I provide a rotarymember or rotor corresponding to each string; and each rotor is provided with circumferentially' tric circuit, at a frequency corresponding to the natural period of vibration .of the vibrator or string, cooperating with amplifying means, and.

eiectro-mechanical means for vibrating the strings.

A further object of the invention is to provide simple means for producing organ tones from an ordinary piano. 1 Further objects of the invention will appear hereinafter.

The invention consists in the novel parts and combination of parts to be described hereinafter,

1 all of which contribute to produce an efllcient magnetic control apparatus for musical instruments.

-A preferred embodiment of the invention is described in the following specification, while the broad scope of the invention is pointed out in the appended claims.

In the drawings: Figure 1 is a diagrammatic view, certain parts being broken away, illustrating the essential features of my apparatus as applied to a piano, and

, illustrating the circuits and switches which may be employed with the invention for producing harmonic tones simultaneously with fundamental tones, the harmonic tones and the fundamental tones being produced by diflerent strings.

Figure 2 is a plan of the forward portion of a piano, withthe keyboard and a portion of the sounding-board broken away, and illustrating 'my improvement applied as an aco'essory'set in place adjacent to the strings.

Figure 3 is a vertical section taken about on the line'3--3 of Figure 2, upon an enlarged scale, certain parts being broken away and illustrating a type of rotor in which the poles of the rotor are excited by coils passing around the same.

Figure 4 is a section taken about on the line 4-4 of Figure 3, certain parts being broken away.

Figure 5 is a vertical section taken about on the line 6-5 of Figure 2, upon an enlarged scale, certain parts beingbroken away, and particularly illustrating a pedal as actuating means for raising or lowering the rotors bodily,'to varyv their distance from the strings, and thereby control the volume of the music produced.

Figure 6 is an end elevation in partial section,

taken about at the locationof the line 8-8 of Figure 2, but upon an enlarged scale. This view a Figure 7 is a vertical section taken about on the line 'Ii of Figure 6, and further illustrating details of means for supporting and adjusting the height of the rotor carriage.

Figure 8 is a detail section taken about on the line 8-8 of Figure 9, and illustrating one of the rotors, and the wiring for the same, certain parts being broken away.

Figure 9 is a side elevation of the rotor illustrated in Figure 8. Figures 8 and 9 both illustrate the relation of each rotor to its corresponding string.

Figure 10 is a diagrammatic view illustrating a type of rotor in which permanent magnets are employed. In this view, certain parts are broken away, or shown in section. This view illustrates a type of construction in which a shield is mounted between the string and the rotor, together with key-controlled means for withdrawing the shield at will, to permit the rotor to vibrate the string.

Figure 11 is a vertical section taken about on the line lI-H of Figure 10, but omitting the shield and the string.

Figure 12 is a diagrammatic view illustrating a special winding and circuit arrangement for a rotor, enabling different sets of the poles to be excited at will.

Figure 13 is a diagrammatic view illustrating a simple embodiment of rotor, in which two elements or poles are employed diametrically opposite to each other, and showing the rotor mounted adjacent to a piano string, for vibrating it, the sounding-board of the piano being shown in section.

Figure 14 is a view similar to Figure 13, but representing a rotor having four poles and of a diilerent type, in which the poles are excited by coils placed around them, and wired into a circuit normally open but capable of being closed by key.

Figure 15 is a view similar to Figure 14, showing the same type of rotor but in which the poles of the rotor are constantly excited. This view illustrates the use of a shield controlled by the key, which, when depressed, effects the withdrawal of the shield to permit the rotor to vibrate the spring. This view also illustrates an electromagnet pickup device located adjacent the string, forproducing impulses in a circuit with a frequency corresponding to the period of vibration of the string.

Figure 16 is a view similar to Figure 15, but illustrating means whereby the string can be struck by the hammer action actuated by the key, the circuitthrough the rotor being closed by the depression of the key. This view also illustrates a pedal with means controlled thereby, for raising or lowering the rotor to vary the volume of tone produced by the string.

Figure 1'7 is a diagrammatic view illustrating the wiring of the poles of a four-pole type of rotor, together with the lead in wires for carrying the current through the exciting coils of the poles.

Figure 18 is a diagrammatic view illustrating another embodiment of the invention, in which I employ a rotor of magnetic material such as soft iron located on one side of the string, and preferably above it, and with an electromagnet located below the string opposite the rotor. This view also illustrates the circuit for the electromagnet with a key for closing the same, together with means for varying the force of the current passing through the coil of the eiectromagnet to vary the volume of the tone produced by the strings.

Figure 19 is a diagrammatic view illustrating a rotor mounted adjacent a vibrator, in the form of a reed carrying an armature, the said armature being located adjacent to the path of the poles of the rotor, and with the coils of the poles in a circuit controlled by key.

Figure 20 is a diagrammatic view illustrating an embodiment of the invention, in which I employ a vibrator such as a tuning fork, in which vibrations are induced in accordance with my invention, so as to develop pulsations in an electric circuit, the said pulsations being amplified so as to enable them to cooperate with an electromagnet adjacent the string for vibrating it.

Figure 21 is a view similar to Figure 20, but illustrating the key-controlled circuit for the rotor, and showing a circuit for carrying an amplified pulsating current connected up to a loud speaker. This view also illustrates a modification of the use of a lateral circuit taken oil from the loud speaker circuit, for energizing an electromagnet to vibrate a string.

Figure 22 is a diagrammatic view illustrating a vibrator such as a diaphragm actuated by a key-controlled circuit passing through a rotor below the diaphragm and cooperating with an armature on the diaphragm. This view illustrates the use of a resonator such as an organ pipe cooperating with the vibrating diaphragm to give increased volume to the tone produced.

Figure 23 is a plan of the apparatus illustrated in Figure 22.

Figure 24 is a diagrammatic view corresponding to Figure l, and illustrating an embodiment of the invention in which the vibrating means for the strings is of the same type illustrated in Figure 18, that is to say, instead of having the poles of the rotors excited by coils on them, the rotors have the form illustrated in Figure 18, so as to enable them to cooperate with corresponding magnets placed on the other side of the strings. This view also illustrates the circuit'arrangement together with switches for enabling harmonic partials to be sounded with strings producing the fundamental tone.

Figure 25 is a diagrammatic view corresponding to Figure 18, and is a vertical section through a stringed instrument, illustrating the same type of rotor, but illustrating another type of means for raising and lowering the carriage on which the electromagnets are mounted. This view illustrates the use of a hydraulic means for raising and lowering the carriage to control the volume of music produced by the rtrings.

Figure 26 is a side elevation of a disc which may be employed in forming a composite rotor, such as illustrated in Figure 28, in which the rotor itself develops harmonic vibrations in the string.

Figure 27 is a view similar to Figure 26, illustrating another disc to be used in forming the composite rotor, and having poles of a different character from the poles employed on the disc shown in Figure 26.

Figure 28 is a side elevation of a rotor of composite type, and formed of a plurality of discs.

Figure 29 is a vertical section taken about on the line 1929 of Figure 28, the shaft of the rotor being broken away.

Figures 30 and 31 illustrate discs of two different types, which may be employed to form a composite disc such as illustrated in Figure 32.

Figure 32 is a side elevationot a composite rotor formed of discs having the character illustrated in Figures 30 and 31.

Figure 33 is a side elevation of a composite rotor composed of discs with poles oi diflerent character, and in which the poles are excited by electric circuits passing around them.

Figure 34 is a diagrammatic view illustrating an embodiment of the invention, in which a l0 rotor of composite type is employed to cooperatewith an electromagnet to vibrate a vibrator such as a reed, the volume of the sound being increased a by the use of a resonator. The circuit through the magnet is illustrated as controlled by one of .15 the piano keys.

Figure 35 is a view similar to Figure 34, but

illustrating another embodiment of the invention,

- in which a vibrator or reedis employed with a resonator above it, and with an electromagnet I below it. In this embodiment of the invention,

the rotor is located below the electromagnet.

Figure 36 is afragmentary view showing two adjacent rotors and a portion 01' the shaft carry,- ing them, broken away.

tion of the invention, it should be stated that in practicing the invention, I provide a rotor 'adja-.

but in other types a single magnet is mounted so as to cooperate with the poles as they pass adjacent to it to develop the magnetic forces period- 40 ically to vibrate the vibrator or string.

A simple embodiment of the invention is illustrated in Figure 13, in which I illustrates a rotor,

carried on a rotating shaft 2 and provided with two diametrically opposite'elements or poles 3 45 and 4. This rotor is mounted adjacent a vibrator, for example, a piano string 5 mounted on, a sounding board 6. On the side of the rotor remote from the string, I provide an electromagnet I having a coil8 which is connected in to an 50 electric circuitthrough the medium of conductors 9 and i0. This circuit is controlled by a piano key corresponding tothisstring. -When the 'key is depressed, the electromagnet l is energized, and when the'poles 3 and 4 are in the position indicated, magnetic forces are induced in them, which attract the string. The shaftl isro'tated at a speed to enable these pole pieces to pass the string at a frequency to correspond with the period of vibration of the string, and vibrate the 60 string. And it is unnecessary to provide the string with an armature to cooperate with the I electromagnet. The string is devoid of an armature.

Figure 14 illustrates another embodiment of 65 the invention, in which the rotor H is provided 75 circuit i1. Between the rotor and the string it,

Before proceeding toa more detailed descrip- In one type of the' a magnetic shield I3 is mounted. This shield is normally interposed between the rotor and the string, and its presence weakens the force of magnetism passing to the string, to such an extent that, the rotation of the rotor will not vibrate the string. By depressing a key 20, the shield can be swung to one side through the agency of the link 2| attached to a bell crank lever 22. One arm of this bell crank lever is connected to the shield, and the shield is mounted in a suitable suspended guide 23 supported from the fixed part or rail 24. If desired, an electromagnet pickup device 25 may be employed, the core of which is mounted adjacent to the string, and this electromagnet device includes a coil 23 connected to circuit wires 21. t

In Figure 16 I illustrate an embodiment of the invention, in which each piano key 23 operates a hammer action 29, which drives a hammer up against the'under side of the string II. This same key closes a circuit 32 through a rotor 33, the shaft 01' the rotor being mounted on a lever 34 that is controlled by a pedal 35 to enable the rotor to be raised or lowered to vary the volume of the tone produced by the string. Twoor more of the levers 34 would be provided, supported on a fixed part or raii,36. Any suitable stop means such as a projection 31 would be provided for limiting the downward movement of the rotors. The pedal 35 may be connected to the lever or levers 34 in any suitable manner, for example, by means of a bell crank lever 33 and a link 33 passing up through an opening in the sounding board 40. If desired, an electromagnet 23a may be fixed over each string and connected in a circuit 21a through an amplifier 21b, the output side of which connects to a loud speaker 210 Vibration of the string 3i when struck by the hammer 30 induces amplified impulses that are translated into sound by the loud speaker.

In Figure 17 I illustrate an enlarged detail of the windings for the poles of the rotor illustrated in Figure 14. This wiring is a common tom of wiring in which the coils on'the poles are connected in series, one end of the connected coils being attached to an insulated contact ring 4i cooperating with a brush 42, and the other end being attached to an insulated contact ring 43 that cooperates with the brush 44. I

In the embodiment of'the invention illustrated in Figure 18, I provide a rotor 45 above the string 43, and this rotor ismade of magnetic material either in the form oi a ring or a disc, and having a plurality of equidistant spaced projections, elements or teeth 41. poles because they simulate the action of the poles 3 and 4 referred to in connection with Figure 13. A plurality of these rotors 45 are mount ed on a shaft 48 extending transversely to the strings 46. Under each string I provide an electromagnet havingan armature 49 that lies near the lower side of the string, and the coil 50 of this electromagnet isconnected into a circuit 5i which can be closed at will by depression of a corresponding piano key 52. If desired, the circuit may includea variable resistance 53 controlled by a foot pedal 54. This will enable the volume or the sound to be controlled at will. As each polef' 41 passes the string, it cooperates with the magnetic lines of force so as to increase the quantity that passed to the rotor. In this way, thepower of the lines of force will be alternately decreased and diminished as the poles pass the string. The number of poles or teeth 41 is such that when I refer to these teeth as I the shaft. is rotated at a uniform speed, they will pass the string with a frequency corresponding to the period of vibration of the string. Hence, whenever the key 52 is depressed, the mag netic lines of force from the magnet cooperating with the rotor, will vibrate the string.

In Figures 8 and 9 I illustrate a type of rotor in which the rotor 55 is in the form of a ring with radial spokes 56 which are integral with the rim of the rotor. These spokes 56 operate as poles, and carry coils 51 which are connected in series. The periphery of the rotor is formed with equidistant teeth or poles" 58. A circuit controlled by the corresponding piano key, is passed through the coils by utilizing brushes 53 and 6C touching the shaft BI and an insulated contact ring 62. This rotor is mounted near the string 63 which it is to vibrate, and is, of course, rotated at a uniform rate of speed so as to have the poles 58 pass the string at the proper frequency for vibrating that string.

In Figures 10 and 11 I illustrate an embodiment of the invention in which I may employ a rotor 64 composed of a plurality of permanent magnets 65. These magnets may be of U form with the poles of adjacent magnets abutting against each other. This rotor is mounted close to the string 66 which it is to vibrate, and between the string and the rotor I provide a shield 61 of soft magnetic metal such as iron. When this shield 'is in place between the rotor and the string, it

absorbs the lines of force and prevents the rotating armature from vibrating the string. Each shield 61 can be withdrawn at will, by depressing the piano key 68 that corresponds to this string. The rear end of this key actuates mechanism 69 including a lever 10 mounted on a fixed pivot 1| which has a pin-and-slot connection 12 with the rear end of the carriage 13, the forward end of which carries the shield. Whenever the carriage or slide 13 is actuated, it slides through a fixed guide 15. As illustrated in Fig. 11, the permanent magnet 65 may be clamped between two side plates 25.

In Figure 12, I illustrate a special construction for a rotor 16, in which the rotor is provided with a plurality of poles disposed in two sets, one set being composed of alternate poles 11, and the other set being composed of alternate poles 18. Each set of poles has its own corresponding series of exciting coils 1S and 80. The coil 19 is connected to an insulated contact ring 5!, and the other coil is connected to an insulated contact ring 82. These rings are in contact with corresponding brushes 83 and 8| that are connected into a circuit by conductors 85 and 86. Corresponding to each of the conductors 85 and 86,

there is provided a relay. These relays are indicated respectively, by the numerals 81a. and 81b. The coils 88 of the relay magnets are wired in parallel by conductors 89 from one side of a source of E. M. F., or battery 90, the other side of the battery being connected to a ground 9|. The other ends of the coils are connected to tappets 92a and 92b, to grounds S3 and 84. The switch member 95 of each relay is normally held open by a spring 96. When the piano key 91 is depressed, it closes a switch 98 that connects conductors 99 and I00, thereby connecting either one of the switch members 95 into a circuit. passing through either one of the series of coils of the rotor. For example, if the tappet 92a has been previously closed, the current will pass through the series of coils that are connected with the brush 83. The current through the switch 92 is supplied from a battery III, one side or which is connected to a contact I22 on the key, the other side of which is connected to a ground I03. The rotor 16 is mounted adjacent to a string I04 that is to be vibrated. 11' only one of the tappets 2a or 921) is closed, half 01' the poles of the armature will be active. Hence, if both tappets are closed, all of the poles will be active, and this will double the number of impulses that the rotor will give to the string at each revolution of the rotor.

In the embodiment of the invention illustrated in Figure 25, I utilize the general principles of construction illustrated in Figure 18, that is to say, I mount the rotors such as rotor I 05 above the corresponding string I". Below the string I provide a magnet carriage or bar I01a, which extends longitudinally under the shaft Illa that carries the rotors. Under each rotor an electromagnet IIIII is provided, the coil of which is connected by circuit wires I59 and H to contacts III and I I2 associated with the rear end of the piano key I I3 that corresponds to this string. The magnet bar is mounted for controlled up and down movement. complish this by mounting the magnet bar on rigid levers I I4 which are supported on fixed fulcrums II5. Suitable means is provided for raising and lowering the carriage at will, to control the volume of sound produced by the strings. In the present instance, I have illustrated pneumatic or hydraulic means for accomplishing this. For this purpose I employ a device that extends or contracts in accordance with internal pressure. For this purpose, I employ a device known as a sylphon H seated on a fixed support II1, the upper end of the sylphon being connected to one of the levers III. This sylphon is expanded internally at will, by a fluid or liquid within a tube III, which extends down and is connected'to a sylphon II! which can be compressed by a pedal I20. An overflow reservoir I2I may be provided for taking care of excess liquid in the tube.

A lower stop I22 is provided for limiting the downward movement of the magnet bar I01, and an upper stop I23 for limiting its upper movement. These stops are preferably adjustable as indicated.

In Figures 26 to 29 inclusive, I illustrate a construction of a rotor I24 which is of composite form, and composed of a plurality of discs I25, I25 and I21. The discs I25 and I26 are illustrated in Figures 26 and 27, removed from the rotor. These discs have equidistant poles such as the poles I28 of the disc I25. The poles of the different discs are located on a different pitch, that is to say, they difler in number so that when the discs are secured together in proper alignment by means of bolts I29, the poles of the discs I26 and I21 will be located between the poles I25 of the disc I25. The poles I28 may be employed in using a rotor 0! this kind for producing fundamental notes, and the intermediate poles employed to produce harmonic vibrations in the string. The poles of the discs I28 and I21 can be tapered if desired, to reduce their mass, and thereby reduce their effect on the lines of iorce as compared with the poles I28. In this way, harmonic vibrations of less force and amplitude can be imparted to the strings. The character 01 these harmonic poles can be varied to control the volume of harmonics. This enables an accurate control by means 01' the rotor, of the quality of the sound produced by a string.

In the present instance, I ac- In Figure 31 I illustrate another format disc and with which I associate a pick-up device I84,

which may be used in i'orming'a composite rotor.

This disc is formed with equidistant poles, but

certain oi the poles have a different outline from the poles intermediate between them. For example, this disc I88 may be provided with a pinrality of equidistant poles I8I having a convex profile, with sharp poles in the form of teeth I82 disposed in between. This disc may be combined with a disc I88 illustrated in Figure 30, in which the poles I84 arein the form of tapered teeth. The poles I8I will have greater eflect on the string than the poles I82 and I84.

In Figure 33 I illustrate a composite rotor I88. in which I employ a disc I88 in the form of a ring with four poles I81 which are in line with spokes or exciting poles I88. These exciting poles I88 carry coils I38 which are connected in series and wired into a circuit such as the circuits described above This circuit would be closed by a corresponding piano key. Ihe periphery; of this rotor has the same pole arrangement as that illustrated in Figure 29, and differs from the rotor illustrated in Figure 29,

. by reason of the provision of the coils and exciting poles.

In Figure 34 I illustrate an adaptation of my invention for cooperation with a resonator such as anorgan pipe I below which a vibrator or reed MI is mounted, said reed carrying an armature I82 to cooperate with a composite rotor I48. Above the armature, and if desired, within the lower end of the organ pipe, an electromagnet I is mounted, the coil of which is connected into a circuit I48 including a piano key I88, and a suitable source of E. M. F. such as a battery I41. The ends oi the reed maybe provided with adjustable weights I88 carried in slots I for tuning the reed. Just inside of the tuning weights, fixed supports I88 may be provided for the reed. Any. suitable means sfich as that illustrated in Figure 6, may be employed for moving the rotor toward or from the reed'to control the volume of the tone produced by the reed and organ pipe If desired, the lower end of the armature I42 may be formed with a tapered tip I51.

A modification of the idea" illustrated in Figure 34 is illustrated in Figure 35, in which the electromagnet I82 is not mounted in the organ pipe I88, but is mounted below the reed I84, and

adjacent the lower end of the electromagnet, a

rotor I88 is mounted. When the key I88 is desound may be controlled by'a rheostat I88 oon-- trolled at will by a pedal or other means not illustrated. I

In Figure 19, I illustrate an embodiment of the invention in which a rotor of the type illustrated in Figure 14 is employed for vibrating a reed I88, the circuit I8I through the coils of the rotor being closed at willby means of contacts on the rear end of a key I82.

In Figure 20, I illustrate another embodiment of the invention in which I employ aresilient vibrator such as a tuning fork I88, which is vi-- brated'bythe action of magnetic lines oi force,

closed at will, by a piano key illustrated diagram matically by a switch I10. Adjacent the electro-magnet I88, the vibrator or string "I to be vibrated, is mounted.

Although if desired, the electro-mechanical means for vibrating the tuning fork may operate upon the same tine that is adjacent to the electromagnet I84, I prefer to have this electro mechanical means cooperate with the other tine I12 of this fork. In the present instance, I illustrate a bipolar rotor I18, the poles of which are diametrically opposite to each other, and this rotor is mounted for rotation below a constantly energized electromagnet I14. This, of course, will produce continuous vibration of both tines of the tuning fork. If the sound produced by the tuning forks tends to produce an audible hum, this diiliculty can be overcome'by simply locating this part of the apparatus a short dis-- tance from the location oi the piano or other instrument, the vibrators of which are actuated directly by the electromagnets I88.

In Figure 21, I illustrate another adaptation of the idea embodied in Figure 20, in which the tuning fork I18 is vibrated by a rotor I18 having exciting coils I11 onits poles, which are connected in an electric circuit I18 closed by a corresponding piano key I18. The lower tine of the tuning fork has a pick-up device I88 mounted adjacent to it, and by this means pulsations are produced in a circuit I8I extending to an amplifler I82. Beyond the amplifier an extension circuit I88 may be provided, including a loud speaker I84, and a tappet I88 for closing this circuit at will. If desired, another extension circuit indicated by dotted lines I88, can be run ofl from the wires of the circuit I88 and connected to 'an electromagnet I81 for vibrating a piano string I88. This enables music to be produced in accordance with my apparatus,-through' a loud speaker, and the same circuits to be employed for playing a piano or organ in another room, or

at a distance from the loud speaker.

In Figures 22 and 23, I illustrate an adaptation of the invention, in which I place a rotor I88 below a vibrator such as a diaphragm I88, the

,said rotor having poles excited by coils connected in a circuit I8I which may be closed at will by a key I82, such as a piano key. This rotor may be mounted in a box, and above the diaphragm an organ pipe I88 may be supported as a resonator. If desired, the upper side of the diaphragm above the shaft of the rotor, may be provided with an armature I88.

While the improvements described hereinabove may be embodied and'built in permanently into 'a piano 'or other instrument, in Figures 2 and 6 I illustrate an embodiment of the invention, in which the magnetic actuators for the strings are constructed as an operative unit and mounted on a carriage I88, said carriage being provided with a plurality of shafts carrying the rotors, said rotors being indicated generally by the numeral I88. 'Ihe carriage is in the formo'f such as the string I98. These strings are devoid of armatures. (See Fig. 3.) By a circuit arrangement which will be described hereinafter, when any key corresponding to a certain rotor is depressed, the circuit will be closed through the coils I99 around the poles 200 of the rotor. The poles are then excited and as each pole passes the string, it attracts the string with a maximum magnetic force. These maximums alternate with periods of minimum attraction as the gap between two poles is passing the string. In the manner described hereinabove, by rotating the shafts at predetermined speeds, and by provlding a predetermined number of poles on each rotor, the poles can be made to pass the strings at a frequency corresponding to the natural period of vibration of the string. This carriage may be employed on an upright piano or on a grand piano. In any case, it should be mounted so that it can be moved toward or away from the strings. The preferred construction for this purpose is illustrated in Figure 6, and consists in supporting the carriage on wedge blocks 20! which rest upon antifriction means such as rollers 202, said rollers being mounted respectively on slide blocks 2" which are guided to slide in grooves such as the goove 204. These blocks 233 are connected to a stem 205, the end of which may have a pin and slot connection 208 with a bell crank lever 201. This bell crank lever may be actuated at will by a control wire 208 carried in a flexible sheath 209 that extends down to a point below the keyboard 2) (see Fig. 2) at which point the end of each wire'is attached to the lower end of a pedal 2 (see Fig. 5). There are preferably two of these control wires which extend in opposite directions to the ends of the carriage, as indicated in Figure 2.

The carriage W5 is preferably guided in its up and down movements on suitable pins 2|2 that pass through suitable guide openings 2|3 in the carriage, and the weight of the carriage and parts carried by it, is counterbalanced by means of coil springs 2H mounted on these pins. The provision of these springs 2 increases the facility of raising the carriage my means of the control wires 208.

The shafts that carry the rotors I85 are preferably composed of three long shafts for operating the bass notes, and three short shafts for operating the treble notes. In Figure 2, 2|! indicates the long shaft which is paired with the corresponding short shaft 2|6. The long shaft 2|! has three sets of rotors indicated by the numerals 2|7, 2|8 and 2|8. There are four rotors in each set. The rotors composing the set 2|1 are mounted on the shaft close together, and are mounted for actuating the four has notes corresponding to the string |08a that produces the lowest note on the scale. This shaft is rotated at approximately two revolutions per second. The rotor 2|ia of this set should have sixteen poles or teeth spaced-equidistant on its periphery, as indicated in Figure 3. The rotor 2|Ib next to it should have seventeen poles or teeth, while the next rotor 2|1c should have eighteen teeth, and the next rotor 2nd should have nineteen teeth. If this shaft is rotated at the stated speed, these rotors will vibrate the strings corresponding to these notes in their natural periods of vibration. The rotor 2| 8a of the set 2|8 is located over the thirteenth note from the bass end of the instrumerit. This rotor should have thirty-two teeth,

and the next rotor in this set should have thirtyfour teeth. the next thirty-six, and the next thirty-eight. With this same speed of rotation of two revolutions per second, these numbers of poles or teeth on the rotors of this set will vibrate their corresponding strings in their natural period of vibration. The rotors of the set 2|! have double the number of teeth or poles as the corresponding rotors of the set 2 I I, that is to say, beginning from the left as viewed in Figure 2, they would have sixty-four teeth, sixty-eight teeth, seventy-two teeth, and seventy-six teeth. The left-hand rotor of this set is located over a string which produces a note that is an octave higher than the corresponding rotor 2 Ila of the set 2|l.

The shaft 2 8 carries three sets of rotors, namely, 220, 22| and 222. This shaft is driven at eight times the speed of the shaft 2|5, the rotors of the set 22' beginning from the left, have 16, 17, 18 and 19 teeth respectively, like the set 2|lo. The set 22| of rotors have the same relation as regards their number of teeth, to the set 220, as the relation of the rotors of the set 2|! to the set 2H, and likewise, the rotors of the set 222 have the same relation as regards their teeth, to the set 22|, that the teeth of the set 2|! have to the teeth of the rotors of the set 2 ll.

The shafting includes an intermediate pair of shafts 223 and 224 which correspond respectively, to the shafts 2|! and 2|6, and each of these shafts carries three,sets of rotors with the same relation of teeth or poles as described in connection with the shafts 2]! and 2| I, that is to say, the left-hand set of rotors on the shaft 223 have 16, 17, 18 and 19 teeth respectively, etc. The

shaft 223 should be driven at 3.17 revolutions per second, and the shaft 224 is driven at eight times that speed. It should be noted that the lefthand set of rotors on the shaft 22!, corresponds to the four strings that are Just to the left of the set 2|l of rotors. The other sets on this shaft are correspondingly located with respect to the corresponding sets on the shaft 2| 5.

The foremost shafts 22! and 220 carry rotors in sets, the same as the other two sets of shafts, and the left-hand set of rotors on the shaft 22', correspond to the four strings just to the right of set 2|! of the shaft 2|, and the rotors of this set have respectively, 16, 17, 18 and 19 teeth or poles. The adjacent set of rotors on this shaft 225, have 32, 34, 36 and 38 teeth respectively, and the left-hand rotor of this second set is over the string corresponding to the first octave above the fifth note of the piano which is played by the left-hand rotor of the first set on this shaft. In the right-hand set of rotors on this shaft 228, the corresponding rotors have double the number of teeth of the intermediate set on this shaft, and the left-hand rotor of the right-hand set is mounted over the string which is an octave higher than the left-hand rotor of the intermediate set. The shaft 220 has three sets of rotors corresponding to the sets 22., 22| and 222 of the shaft 2|0, and disposed so as to lie over the next four strings to the right of each of the other sets. The rotors of the left-hand set on shaft 228 have 16, 17, 18, and 19 teeth respectively, and the corresponding rotors in the intermediate set on this shaft, have double this number of teeth. like-- wise, the rotors in the right-hand set on the shaft 228 have double the number of teeth of the corresponding rotors in the intermediate set on this shaft 228.

The shaft 228 is rotated at a speed of 2.52 revolutions per second, and the shaft 220 has eight times this speed of rotation.

40 inafter.

The shafts may be driven at the necessary predetermined speeds by gearing or by any other suitable means. I prefer however, to drive these shafts with belts, on account of the fact that the speed ratio from each shaft of lower rotation to each corresponding shaft of higher rotation, is 1.26.

In Figure 2, I have illustrated a belt drive a from an electric motor 221 that is mounted on. the carriage I55. I prefer to drive the relatively slow moving shafts 2l5, 223, and 225 on one belt 225, and the relatively fast moving shafts on another belt 223. These belts run over two adjacent pulleys on the shaft 230 of the motor, and pass around corresponding pulleys 232 and and the pulleys on the shaft 230, are such as to give the shafts the proper predetermined speed. In Figure 1, I illustrate diagrammatically, the

, essential features of the wiring arrangement corresponding tothe rotor arrangement illustrated in Figure 2. This view however, shows only the three shafts 2i5, 223,1and 225, but the wiring arrangement is substantially the same for the short shafts. As illustrated in Figure 1, each rotor such as the rotor 2 Ha is provided with poles such as the poles 200, and, carrying winding such as the winding 199. One end of each winding is attached to a corresponding insulated collar 234 on the shaft, and the other end .of the winding is connected to another insulated collar 235.

'35 Each collar 234 has a corresponding brush 235,

and each collar 235' has a corresponding brush 231. The brushes 235 are connected to suitable conductors and switches with corresponding keys of the piano keyboard, as will be described here- The other brushes 231 are connected in parallel by conductors 235 leading off from a trunk wire 239, which trunk is connected with a source of E. other side of which is connected to a ground I The wiring arrangement for the different shafts, is substantially the same as that described above. Interposed between the keys 242 and their corresponding brushes 235, in the wiring 50 system, I provide a plurality'of switches, for ex- 55 partial" switch 245. These switches may .be

closed at will by the player. Any suitable means may be employed for this purpose. In the present instance, I illustrate electric means for this purpose. In order to accomplish this, each of 00 the switches may be in the form of a shaft carrying a rigid arm 241, which operates as an armature for an electromagnet 248. When the coil of F. such as a battery 240, the

struck, then the depression of the first bass key will close, a circuit through the individual fundamental switch 2434; from a contact 25l at the rear end of the piano key, which is struck by a contact plate 252 on the key. This closes a circuit through conductor 253, through the individual switch 243a, and through conductor 254 that leads up to the brush 235. For each key 242 of the keyboard, there is a contact corresponding to the contact 251 so that when any key is depressed, a circuit will be closed to operate its corresponding string. In order to accomplish this, all of the contact plates 252 are preferably wired in parallel through the agency of conductors 255, which connect to a trunk line 255 connected to a ground 251 at one side, and. passing all the keys. The circuit arrangement for playing a "second partial corresponding to any lower note sounded, is substantially the same as described in my prior Patent No. 2,006,443, granted July 2, 1935, on an Electrically controlled piano. However, in the present instance, I provide different resistances for the second and "third partials, as will now be described. Suppose for example, that the first bass note of the keyboard is struck. This will vibrate the corresponding string I951: which produces the lowest .note on the scale. In-addition to this, a circuit will be closed by way of a contact 250 alongside of the contact 25l, said contact 250 being connected by a conductor 25! to a terminal 252, and thence through a. relatively low resistance 253 to a switch contact 254 corresponding to an individual switch 255 of the second partial switch 244. If this switch 244 has been closed, the individual switch 255 will be closed, setting up a circuit through the movable switch member 256, and through a conductor 251 up to the brush corresponding to the rotor 2l8a already described.

This rotor is located over a string l98b which will give an octave of the first note of the piano.

There is wiring corresponding to this described, for all of the keys, except of course, the treble keys which are too near the upper end of the scale to permit of theirhaving any higher partials or harmonics that can be played on that instrument.

If the second partial switch 245 has been closed instead of the second partial switch 244,

current will flow from the terminal 252 down through a relatively large resistance 258 to the corresponding contact point 259 of an individual switch 210 of the second partial switch 245, and from this point current will flow through the movable switch member 215 through the wire 251, up to the rotor 2l8a. This will sound the same note asis sounded when the switch 255 is closed, but gives the partial a reduced volume.

In this way, by employing two second partial" the magnet 248 is energized, the corresponding multiple switch will be closed. For example,

65 when a tappet 249 corre ponding to thefunda- 7 of the keys 242, so that when any of thenkeys 242 is depressed, a circuit corresponding to its liimeplanovsl y s will be closed through the rotor over 7 that strin'gTFor' example, assuming that the fundamental switch 243 has been closed, and as- 75 suming that the first note of the scale is to be switches, I can sound a second partial note or harmonic with two different volumes, thereby changing the timbre of any tone. If the "third partial switch 245 has been closed before the first bass key 242 has been struck, then a circuit will be set up for producing a third partial" harmonic corresponding to the first string of the plane. In order to accomplish this, I provide a third contact 21l which is connected to a conductor 212'that extends to a contact 213 corresponding to an individual switch 214 of the thirdpartial multiple switch 245, and if this third partial switch 245 has been closed, then current will flow from the 'fixed contact 213 through the movable contact 215 of the individual switch 214, and will pass up'by wire 215 to the brush 211 that corresponds to rotor 219 on the shaft 225, and which is located over a string I99c of the piano, which will give a third partial harmonic corresponding to the first string of the bass.

Figure 24 is similar to Figure l, and. illustrates the essential features of a general arrangement of rotors and wiring, etc. The arrangement in this view is substantially the same as in Figure 1, except that the rotors illustrated, do not have electrically excited poles. In other words, the rotors are of the type illustrated in Figure 25, and below each rotor I provide an electro-magnet 219 which is located below the corresponding string 299, and preferably mounted on a carriage such as the carriage or magnet bar I91. These electromagnets 219 are wired in parallel on branch conductors 29I from a main conductor 292 connected to one side of a battery 293, the other side of which is connected to a ground 294. Beyondeach electro-magnet 219 a circuit wire 295 is provided that corresponds to the wires 254 referred to in Figure 1. In other words, each of thesewires 295 leads down to the corresponding individual switch 299 controlled by a multiple first partial switch 291, said multiple switch 291 being controlled by an electro-magnet 299 through a circuit 299 including a tappet 299 for controlling it. This arrangement also includes two second partial switches 29I and 292 corresponding to the switches 244 and 245 already described and wired in the same way to enable the second partials" to be sounded in diiferent volumes, according to whichever one of the switches 29I and 292 is closed. In this Figure 24,,the shafts 299, 294 and 295 that'carry the rotors 299 corresponding to the shafts 2I9,

223 and 225, and have the same arrangement of rotors upon them. The rotors have the same arrangement of poles, and the relation of the number of poles is also the same as described in connection with Figures 1 and 2. The advantage of using plain rotors of disc-form as illustrated in Figure 24, ascompared with the wired type of rotor, is that a much simpler construction attains the desired results. In other words, the single electromagnet 219 avoids the necessity for winding all of the rotors with wires. The vibration of the strings is, of course, brought about by induced magnetic forces as each pole of an armature passes the electromagnet 219. If a piano key 299 corresponding to a certain string has been pressed down, a circuit set up through the fundamental switch, and passing through either of the "second partial" switches will be closed, energizing the corresponding electromagnet 219, so that the string corresponding to the key, will be vibrated.

The general mode of operation of the apparatus will now be briefly described. In the embodiment illustrated in Figures 1 and 2, by pressing the proper tappet 249, the corresponding electromagnet 249 for the fundamental switch 249 will eflect the closing of this switch. This will set up circuits 'hrough all of the windings of the rotors, ready to be closed by the depression of any key. Whenever any key is depressed, for example, the key 242 /(see PIE. 1) the contacts HI and 252 close the circuit through. the corresponding rotor 2I1a, and this energizes the poles of this rotor. The shaft 2 I5 is being driven at a speed such that as the sixteen poles of this rotor pass the string Illa, a series of attractive impulses will be given to the string corresponding to its period of vibration. This will cause the string to vibrate and produce its musical tone. If the tappet 249 corresponding to the sec ond partial switch 244 has been closed, then this switch will be closed in addition to the fundamental switch 243." When any piano key, for example, the key 242 is depressed, a circuit will be closed from contact 299 and through the wire 29I, and through resistance 299 and individual switch member 299 to the wire 291, and this will energize the rotor 2I9a and vibrate the string below it so as to produce a harmonic tone corresponding to the first has note produced by the lowest bass string of the piano. If the switch 245 is closed instead of the switch 244, then the .same rotor 2I9a will be energized, but the current will be reduced by reason of the increased resistance 299. This reduces the volume of the harmonic tone produced by the string below this rotor 2I9a.

By rocking the pedal 2 (see Fig. 5) up or down, the control wires 299 will operate the bell crank lever 291 (see Fig. 6) and this will move the slides 293 in or out under the wedges 29I, thereby raising or lowering the carriage I95 that supports all the rotors. In this way, the volume of the music produced by all the strings is controlled. When the rotors are constructed as illustrated in Fig. 24 and Fig. 25, the circuit closed by any key, does not pass through any winding on the rotors, because these rotors have no windings, but are plain metal discs with teeth or poles which pass above their corresponding electromagnets 219 through which the circuit is closed. This will cause vibration of the string.

The magnets 219 are preferably mounted in the manner illustrated in Fig. 25, enabling the bar- I91 that carries the magnets, to be raised or lowered at will by rocking the pedal I29. This movement is effected through a hydraulic tubing II9.

By employing a rotor composed of discs with different character of poles as illustrated in Fig. 28, the rotors themselves can produce harmonic vibrations in the string.

In the embodiment of the invention illustrated in Figure 10, in which permanent magnets are employed on the rotors, the effect of the magnetism on each string is eliminated by the shield 91,

and each shield is connected with a corresponding key so that when the key is depressed, the shield will be withdrawn and the corresponding string will be vibrated.

What I claim is:

1. In a magnetically controlled stringed instrument, the combination of a plurality of strings mounted for vibration to produce the different notes of a musical scale, a shaft mounted for rotation and extending past the strings, ro-

tary members mounted on the shaft corresponding to the different strings, said rotary members having circumferentially disposed equidistant poles operating to pass their corresponding strings as the shaft rotates, and means for rotating the shaft at a speed to cause the poles to pass the strings at a frequency corresponding to the period of vibration of the strings.

2. In a magnetically controlled stringed instrument, the combination of a plurality of strings mounted for vibration to produce the different notes of a musical scale,- a plurality of shafts mounted for rotation and extending transversely of the strings, sets of rotary members mounted on the said shafts, the rotary members of each set having a plurality of circumferentially dis- ,posed equidistant poles, the number of said poles ment, the combination of a plurality of strings mounted for vibration to produce the diil'erent notes of a musical scale, a plurality of shafts mounted for rotation and extending transversely of the strings, sets of rotary members mounted on the said shafts, the rotary members of each set having a plurality of circumferentially disposed equidistant poles, the number of said poles on the rotary members increasing gradually from the strings corresponding to the low notes of the scale-toward the strings corresponding to the higher notes of the scale, means for rotating the shafts, a. carriage. supporting all of the shafts, and means for controlling the said carriage at will to move .the rotary members toward or from the strings to control the volume of the sounds produced by the vibration of the strings.

4. In a magnetically controlled musical instrument, the combinationof a plurality of vibrators for producing notes and octaves on a musical scale, keys corresponding to the vibrators, circuits corresponding to the keys and vibrators with means adjacent the vibrators for sounding the same when the correspondingkey closes the circuit to the vibrator, a second parspectively and, having circumferentially spaced elements moving in a path near the vibrators as the rotary members revolve, said elements operating to oscillate the vibrators as they pass the same, and key-controlled means for effecting the production of the different musical notes.

6. In a magnetically controlled musical instrument, the combination of a plurality of vibrators for producing the difl'eren notes of a musical scale, rotary members mounted for rotation ad jacent the vibrators respectively and having circumferentially spaced elements moving through a path near the vibrators as the rotary members/re- -,volve, and magnetic means associated with the rotary members to develop magnetic forces acting on the vibrators when each element passes the same.

7,. In a magnetically controlled musicalinstrument, the combination of a plurality of vibrators .-for producing the different notesof a musical scale, rotary members mounted for rotation adjacent the vibrators respectively and circumferentially spaced elements moving through a path near the vibrators as the rotary member revolves, magnetic means associated with the rotary members respectively to develop magnetic forces acting on the vibrators while the said spaced elements are'passing the same, and handoperated means for controlling the magnetic attraction of the said elements for the vibrators.

8. In a magnetically controlled musical instrument, the combination of a plurality of vibrators, a plurality of rotary members of magnetic material mounted for rotation adjacent the vibrators respectively, said rotary members each having circumferentially *spaced poles moving in a path near the vibrators as the rotary member is revolved, electrical means for exciting'the poles, including an electric circuit passing to the same respectively, and a key in each circuit for closing the same at will. 7 e

9. In a magnetically controlled musical instru ment, the combination of a vibrator, a rotary member composed of a'magnetic material, mounted for rotation adjacent the vibrator, said rotary member having equidistant circumferentially spaced poles moving through a path near the vibrator as the rotary member revolves, a frame mounted for movement toward or from the vibrator, an electromagnet mounted on the frame and disposed adjacent the vibrator, and a keycontrolled electric circuit passing through the said electromagnet, said electromagnet cooperating with its corresponding rotary member as each pole passes the vibrator, to develop magnetic forces for actuating the vibrator. L

10. In a magnetically controlled musical instrument, the combination of a string devoid of an armature and mounted to vibrate, a continuously driven rotary member located adjacent the string, an electromagnet mounted adjacent the string and on the side thereof remote from the said rotary member, a circuit passing through the electromagnet, a key for closing the circuit, and means controlled at will for regulating the attractive force developed by the current passing through the electromagnet, said rotary member and said electromagnet cooperating to vibrate the string.

11. Ina magnetically controlled musical instru-' ment, the combination of a plurality of vibrators for producing the diflerent notes of a musical scale, rotary members corresponding respectively to the different vibrators, said rotary members being of magnetic material and mounted for rotation adjacent their corresponding vibrators and having circumferentially spaced projections moving in a path near the vibrators as the rotary members revolve, a carriage located on theop- 'posite side of the vibrators from the rotary memcarriage toward or from the vibrators to alter the volume of the sound produced thereby, said projections cooperating with the said magnets to oscillate the vibrators as they pass the same.

," e vrc'roa nsnvamr. 

